In recent years, there has been increasing demand for high-speed communication in a wireless communication. As a method for meeting such a demand, there has been a method of increasing a frequency bandwidth in a wireless channel used for the wireless communication. On the other hand, a wireless frequency band is a valuable resource used in various applications and has been demanded to be efficiently utilized. In consideration of such a circumstance, it is desired to improve a utilization efficiency of the frequency band that is the valuable resource as well as to attain coexistence with existing wireless technologies. As a method for increasing the frequency bandwidth in the wireless channel while improving the utilization efficiency of the frequency band in this way, a technology is effective which performs a broadband wireless communication by simultaneously using a plurality of wireless channels.
For example, with respect to a wireless channel having 20 MHz width given as a primary channel, a channel to use is extended from the primary channel by adding a channel selected preferentially from an adjacent channel such that the wireless channels are simultaneously used. This achieves a high speed wireless communication with a 160 MHz width at most. In order to simultaneously use the plurality of wireless channels, information on an available channel is shared in advance on transmission and reception sides by way of exchanging a control frame to decide a bandwidth used for transmitting and receiving data.
In the scheme described above for using simultaneously using the plurality of wireless channels, there is one common channel (primary channel) as a system, and channels are sequentially selected from an adjacent channel and added to the common channel. For this reason, the common channel and the adjacent channel close to the common channel are used highly frequently, resulting in high utilization efficiency, but a channel far from the common channel, in spite of being available, is used low frequently, disadvantageously causing low utilization efficiency.
In this way, in the related scheme for simultaneously using the plurality of channels, there has been a problem that the channel lowered in the utilization efficiency exists in view of the whole channels, which lowers the whole channels utilization efficiency.